Hello,
As far as I know, that’s now the way it works. You can’t choose the package before the listing. Unless ihor or andrii can point you to the right direction and come up with an awesome solution.
If you want to assign a default package to user, here’s a possible solution, and you may start building from here.
Basically, you already have a valid “premium” package, then your listing will be able to have the extra features that come with it.
Maybe you can edit the feature afterwards, once you selected the package, with the exception of the categories, which are set once and for all.
My 2 cents,